package accesstoken

import (
	"context"
	"crypto/ed25519"
	"crypto/rand"
	"encoding/hex"
	"fmt"
	"sync"
	"time"

	"gitlink.org.cn/cloudream/common/pkgs/async"
	"gitlink.org.cn/cloudream/common/pkgs/logger"
	stgglb "gitlink.org.cn/cloudream/jcs-pub/common/globals"
	"gitlink.org.cn/cloudream/jcs-pub/common/pkgs/accesstoken"
	"gitlink.org.cn/cloudream/jcs-pub/common/pkgs/rpc"
	corrpc "gitlink.org.cn/cloudream/jcs-pub/common/pkgs/rpc/coordinator"
	cortypes "gitlink.org.cn/cloudream/jcs-pub/coordinator/types"
)

type KeeperEvent interface {
	IsAccessTokenKeeper() bool
}

type ExitEvent struct {
	KeeperEvent
	Err error
}

type Keeper struct {
	cfg     Config
	enabled bool
	token   cortypes.UserAccessToken
	priKey  ed25519.PrivateKey
	lock    sync.RWMutex
	done    chan any
}

func New(cfg Config, tempCli *corrpc.TempClient) (*Keeper, error) {
	loginResp, cerr := tempCli.UserLogin(context.Background(), &corrpc.UserLogin{
		Account:  cfg.Account,
		Password: cfg.Password,
	})
	if cerr != nil {
		return nil, fmt.Errorf("login: %w", cerr.ToError())
	}

	priKey, err := hex.DecodeString(loginResp.PrivateKey)
	if err != nil {
		return nil, fmt.Errorf("decode private key: %w", err)
	}

	return &Keeper{
		cfg:     cfg,
		enabled: true,
		token:   loginResp.Token,
		priKey:  priKey,
		done:    make(chan any, 1),
	}, nil
}

func NewDisabled() *Keeper {
	return &Keeper{
		done:    make(chan any, 1),
		enabled: false,
	}
}

func (k *Keeper) Start() *async.UnboundChannel[KeeperEvent] {
	log := logger.WithField("Mod", "Keeper")

	ch := async.NewUnboundChannel[KeeperEvent]()

	go func() {
		if !k.enabled {
			return
		}

		k.lock.RLock()
		log.Infof("login success, token expires at %v", k.token.ExpiresAt)
		k.lock.RUnlock()

		ticker := time.NewTicker(time.Minute)
		defer ticker.Stop()

	loop:
		for {
			select {
			case <-k.done:
				break loop

			case <-ticker.C:
				k.lock.RLock()
				token := k.token
				k.lock.RUnlock()

				// 当前Token已经过期，说明之前的刷新都失败了，打个日志
				if time.Now().After(token.ExpiresAt) {
					log.Warnf("token expired at %v !", token.ExpiresAt)
				}

				// 在Token到期前5分钟时就要开始刷新Token

				tokenDeadline := token.ExpiresAt.Add(-time.Minute * 5)
				if time.Now().Before(tokenDeadline) {
					continue
				}

				corCli := stgglb.CoordinatorRPCPool.Get()
				refResp, cerr := corCli.UserRefreshToken(context.Background(), &corrpc.UserRefreshToken{})
				if cerr != nil {
					log.Warnf("refresh token: %v", cerr)
					corCli.Release()
					continue
				}

				priKey, err := hex.DecodeString(refResp.PrivateKey)
				if err != nil {
					log.Warnf("decode private key: %v", err)
					corCli.Release()
					continue
				}

				log.Infof("refresh token success, new token expires at %v", refResp.Token.ExpiresAt)

				k.lock.Lock()
				k.token = refResp.Token
				k.priKey = priKey
				k.lock.Unlock()

				corCli.Release()
			}
		}
		ch.Send(ExitEvent{})
	}()

	return ch
}

func (k *Keeper) Stop() {
	select {
	case k.done <- true:
	default:
	}
}

func (k *Keeper) GetAuthInfo() (rpc.AccessTokenAuthInfo, error) {
	if !k.enabled {
		return rpc.AccessTokenAuthInfo{}, fmt.Errorf("function disabled")
	}

	k.lock.RLock()
	token := k.token
	k.lock.RUnlock()

	bytes := make([]byte, 8)

	_, err := rand.Read(bytes)
	if err != nil {
		return rpc.AccessTokenAuthInfo{}, fmt.Errorf("generate nonce: %w", err)
	}

	nonce := hex.EncodeToString(bytes)
	stringToSign := accesstoken.MakeStringToSign(token.UserID, token.TokenID, nonce)

	signBytes := ed25519.Sign(k.priKey, []byte(stringToSign))
	signature := hex.EncodeToString(signBytes)

	return rpc.AccessTokenAuthInfo{
		UserID:        token.UserID,
		AccessTokenID: token.TokenID,
		Nonce:         nonce,
		Signature:     signature,
	}, nil
}